Detection of cable connections for electronic devices

ABSTRACT

Embodiments of the invention are generally directed to detection of cable connections for electronic devices. An embodiment of an apparatus includes a port for the connection of a cable, the port being compatible with a first protocol and a second protocol, the port including a connector for the second protocol, the port including multiple pins including a first pin and a second pin. The apparatus further includes a pull-up resistor coupled between the first pin and a voltage source, a pull-down resistor coupled between the second pin and ground, and a voltage detection element coupled with the second pin. The apparatus is to determine that a cable compatible with the first protocol is connected to the port if the voltage detection element detects a voltage above a first threshold.

RELATED APPLICATIONS

This application is related to and claims priority to U.S. ProvisionalPatent Application No. 61/360,428, filed Jun. 30, 2010, and suchapplication is incorporated herein by reference.

TECHNICAL FIELD

Embodiments of the invention generally relate to the field of electronicdevices and, more particularly, to detection of cable connections forelectronic devices.

BACKGROUND

As the capabilities and functions of electronic devices, and inparticular mobile devices, have proliferated, there are more situationsin which such devices may be connected together. Such devices may beconnected together via a cable to provide various functions.

For example, a mobile device may be connected via a cable with a devicein order to present data. The mobile device may contain data, such ashigh-definition video data, for display, and the mobile device thus maybe connected to a television or other device for the purpose ofdisplaying the data on the device.

However, there are numerous different connection protocols that mayrelated to a device such as a television, resulting in a confusingvariety of ports and connectors installed in display systems.

It is possible to utilize a connector for multiple purposes in order tominimize the number of connectors needed. However, but this may resultin complications in certain circumstances. Identification of the type ofdevice attached to an opposite end of a cable is generally required,which may result in problems if expected signals are not received. Ifthere is difficulty in identification of connected devices, the use ofpins or connections for multiple different purposes for a connector mayresult in the application of improper signal to devices, which maycreate errors or, in certain circumstances, potential damage to adevice.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example, and notby way of limitation, in the figures of the accompanying drawings inwhich like reference numerals refer to similar elements.

FIG. 1 is an illustration of an embodiment of detection of possiblecable connections between devices;

FIG. 2 is a flowchart to illustrate an embodiment of a process fordetection of a cable connection;

FIG. 3 illustrates an embodiment of a cable for connection of devices;

FIG. 4 illustrates an embodiment of a sink device to detect cableconnections;

FIG. 5A is an illustration of pins for a cable connection to a sourcedevice in an embodiment of a system;

FIG. 5B is an illustration of pins for a cable connection to a sinkdevice in an embodiment of a system;

FIG. 6A is an illustration of parameters for an embodiment of a sinkdevice to detect cable connections;

FIG. 6B is an illustration of a parameter for an embodiment of a cablefor connection of a source device to a sink device; and

FIG. 7 illustrates an embodiment of an electronic device.

SUMMARY

Embodiments of the invention are generally directed to detection ofcable connections for electronic devices.

In a first aspect of the invention, an embodiment of an apparatusincludes a port for the connection of a cable, the port being compatiblewith a first protocol and a second protocol, the port including aconnector for the second protocol, the port including multiple pinsincluding a first pin and a second pin. The apparatus further includes apull-up resistor coupled between the first pin and a voltage source, apull-down resistor coupled between the second pin and ground, and avoltage detection element coupled with the second pin. The apparatus isto determine that a cable compatible with the first protocol isconnected to the port if the voltage detection element detects a voltageabove a first threshold.

In a second aspect of the invention, an embodiment of a system includesa sink device that is compatible with a first protocol and a secondprotocol, the sink device including a port having a connector for thesecond protocol, the port including multiple pins including a first pinand a second pin, a pull-up resistor coupled between the first pin and avoltage source, a pull-down resistor coupled between the second pin andground, and a voltage detection element coupled with the second pin. Thesystem further includes a cable coupled with the sink device, the cableincluding a connector for the second protocol, the connector including afirst pin to connect with the first pin of the port and a second pin toconnect with the second pin of the port, the cable including a resistorbetween the first pin of the cable connector and the second pin of thecable connector. The sink device is to determine that the cable iscompatible with the first protocol if the voltage detection elementdetects a voltage above a first threshold.

In a third aspect of the invention, an embodiment of a method includesconnecting a first pin of a connector of a device to a first end of apull-up resistor, a second end of the pull-up resistor being coupledwith a voltage source, the device being compatible with a first protocoland a second protocol, the pull-up resistor being required for thesecond protocol. The method further includes connecting a second pin ofthe connector of the device to a first end of a pull-down resistor and anode, a second end of the pull-down resistor being coupled with ground,and detecting a voltage on the node. The method includes determining bythe device that a cable compatible with the first protocol is coupledwith the connector if the detected voltage is above a threshold voltage.

DETAILED DESCRIPTION

Embodiments of the invention are generally directed to detection ofcable connections for electronic devices.

In some embodiments, a receiving device, or sink device, operates toidentify a type of cable for a transmitting device, or source device,attached to the sink device via a cable connection. In some embodiments,the cable may be connected to a port of the sink device that is reusedfor multiple protocols. In some embodiments, the sink device is able todetect the type of cable connection even if, for example, the sourcedevice has insufficient power and thus cannot provide signaling for adiscovery sequence that is normally used to identify the sink device.

Data source devices may provide data in utilizing various protocols. Inan example, a device may provide video data, and in particularhigh-definition video data, using certain protocols, including HDMI™(High Definition Multimedia Interface) (HDMI 1.4 Specification, issuedMay 28, 2009) and MHL™ (Mobile High-Definition Link) (MHL 1.0Specification, issued Jun. 30, 2010) data protocols. MHL is an interfaceprotocol that provides for connection of a mobile device to an HDMIdisplay device. MHL shares a connector with USB (Universal Serial Bus)at the mobile side and shares a connector with HDMI at the display side.In this manner, neither a mobile device nor a display device requires anadditional new connector to support MHL.

However, in operation a display device is required to determine thenature of a connected source device, such as whether the source deviceis an HDMI source, an MHL source, or a USB device that is erroneouslyconnected to an MHL/HDMI cable. In the interconnection of a sourcedevice to a device such as a dual-mode MHL/HDMI compatible sink,identifying the type of source device from the sink device side isimportant because of the state of a pin that may receive power from oneof the connected devices (the pin being referred to here as the powerpin). For MHL operation, power is provided by an MHL sink device to anMHL source device on the power pin. In contrast with the MHL protocolrequirements, a voltage is supplied on the power pin in the reversedirection in an HDMI connection, from the HDMI source device to aconnected HDMI sink device. The provision of the power signal from theMHL sink device to the MHL source device enables the sink device (beinga display device) to provide power to charge the battery of the sourcedevice (being a mobile device that is generally running on batterypower).

However, a battery drained mobile device cannot initiate the discoverysequence provided for MHL protocol, and a successful discovery sequenceis necessary for subsequent MHL operations. In some embodiments, if asink device can identify a cable connection (and thus a dischargedsource device), it is possible to charge the source unit without therequirement of proceeding through the discovery sequence. If a sinkdevice were instead designed such that power was available all times,then the source device would not need to be identified. However, thisimplementation would create certain complications, including:

(1) The constant provision of power increases the stand-by powerrequirements of the display device.

(2) Because of the sharing of MHL and HDMI connectors at the sink deviceend, the provision of power on the power pin creates a power conflictwhen the display device is connected with a legacy HDMI source device,which would normally supply power on this pin.

In some embodiments, a mechanism operates to detect a cable connectionof a certain protocol. In some embodiments, a detection mechanism mayinclude a sink device compatible with a first interface protocol (MHL)compatible sink and a second interface protocol (HDMI), and a cableconnect mechanism with a connector for the second protocol (such as anHDMI Type A connector), where the sink device operates to sense avoltage that is generated using a pull-up resistor and voltage requiredfor the second protocol.

In some embodiments, in a system for detection of a cable connected toan sink device, if a voltage on a sense pin (CD_SENSE) of a connectorreceptacle is less than or equal to a lower threshold voltage, then thesink device determines that no first protocol (such as MHL) cable isattached. If the voltage on the sense pin of the receptacle is greaterthan or equal to a higher threshold voltage, then the sink devicedetermines that the cable is attached.

In some embodiments, the sensing operation determines whether there isan MHL cable is attached to a sink device, where the sink device iscompatible with MHL and HDMI. However, embodiments are not limited toany particular kind of cable. In some embodiments, resistor levels maybe modified to detect more than one type of cable.

In some embodiments, a cable has a certain resistance (such as 3 KΩ)added between two pins, where such resistance is small enough so as notto affect the sensing voltage, the resistance value being significantlysmaller than a value of, for example, 47 KΩ (which is a required valuefor an HDMI compatible device) and 300 KΩ, but large enough that, ifthere a connection to a device (such as an HDMI device) that is pulledto ground, the resistance may provide protection for the short toground. In some embodiments, resistance values may be selected for easymanufacture, but this is not necessary. In some embodiments, the cableresistance may be modified for different implementations.

FIG. 1 is an illustration of an embodiment of detection of possiblecable connections between devices. In some embodiments, a data sourcedevice such as a source device 105 is connected via a cable 110 to adata sink device. In some embodiments, the cable 110 utilizes connectorsfor ports that reused for multiple protocols. For example, the port atthe source device end 125 may be an MHL port, which is a reused USBport. Further, the port at the sink end of the cable 110 could be anHDMI port, such as port 135 of Device B 120, a single-mode HDMI device,or an MHL port, such as port 130 of Device A 115, a dual-mode HDMI/MHLdevice. (While FIG. 1 illustrates device 105 as being connected toDevice A and Device B, this is intended as an alternative, and not anindication that device 105 is connected to both simultaneously.)

In this illustration, if the cable is connected to Device A 115, then itis not apparent simply from the connection of the cable what type ofdevice the source device 105 might be. The source device could be anHDMI device, an MHL device, or an incorrectly connected USB connection(in which an MHL cable is incorrectly plugged into a USB port of anon-MHL device).

A protocol related to source device 105 often will include a discoveryprocess to be followed when devices are connected. For example, MHLprotocol includes a discovery sequence for the connection of an MHL sinkdevice and source device. However, the discovery sequence requires theoperation of the MHL mobile device, which will not be possible if theMHL mobile device is running battery power and the battery is dischargedto a level that is too low to run the device. In some embodiments,Device A provides for determination of the type of device Source Device105 is without the Source Device having sufficient power to complete thediscovery process for MHL. In some embodiment, upon discovering that theSource Device is an MHL compatible device, Device A 115 provides powerto a pin of the connector 130 to charge the battery of Device A 115.

FIG. 2 is a flowchart to illustrate an embodiment of a process fordetection of a cable connection. In some embodiments, a sink device iscompatible with a first protocol, such as, for example, MHL, with thesink device including a cable connector that is compatible with a secondprotocol, such as HDMI 205. In some embodiments, the sink device may bea device that is compatible with multiple protocols, such as MHL andHDMI. In some embodiments, a cable for the first protocol may include aconnector plug for the second protocol, such as a cable for a connectionbetween an MHL source device and an MHL sink device that utilizes anHDMI connector. In some embodiments, the cable includes a resistancebetween a first pin and a second pin of the connector plug 210, wheresuch pins are not used for transport of signals between the sourcedevice and the sink device. In an example, the connection may be betweena #15 pin and a #2 pin of an HDMI connector. In some embodiments, theresistive connection between the first pin and the second pin may beutilized in the detection of the cable connection by a sink device.

In some embodiments, a cable may be connected to the sink device via theconnector of the sink device 215. Upon receiving such cable, the sinkdevice is not initially aware of the type of device that may beconnected to the sink device via the cable. As illustrated in FIG. 3,the cable includes a connection between the first and second pins. Insome embodiments, the connection of the cable to the sink device resultsin the first pin of the connector being connected to a pull-up resistor220. In some embodiments, the pull-up resistor of a certain value may berequired for a connection in the second protocol, such a clock data pinconnection having a pull-up resistor with a typical value of 47 KΩ. Insome embodiments, the connection of the cable to the sink device resultsin the second pin of the connector being connected a sensing nodedesignated herein as CD_SENSE (Cable Detect Sensing) 225, which mayinclude a pull-down resistor and pull-down capacitor tied to ground, asillustrated in FIG. 4. In some embodiments, the second pin is not usedfor data transmission in the second protocol, such as, for example, ashield pin in the second protocol (a TMDS (Transition MinimizedDifferential Signaling) data shield in HDMI), and thus is available formodification for cable detection use.

In some embodiments, the sink device operates to detect a voltage on thesecond pin 230. In some embodiments, if the detected voltage is greaterthan a first threshold 235, where the voltage is indicative of voltagedrop generated by the current path made possible by the connection ofthe cable and the linking of the first and second pins, then the sinkdevice determines that the cable is a first protocol device cable 240,such as an MHL cable, and the sink device operates consistently withdiscovery of a device under the first protocol, such as driving avoltage on a bus (VBUS) 245 and continuing with first protocol deviceprocess 250. In some embodiments, if the voltage is not greater than thefirst threshold 235 and is less than a second threshold 255, then thecable is not a first protocol device cable 260, and the process mayproceed with other operations under a different protocol 265. In someembodiments, the sink device may proceed with other operations, such as,for example, one or more processes for a second protocol device, such asan HDMI device. If the voltage falls between the thresholds, then theresult may be undetermined 270.

FIG. 3 illustrates an embodiment of a cable for connection of device. Insome embodiments, a cable 300 for a first protocol may include aconnector 310 (such as connector plug) that is compatible with a secondprotocol, such as, for example, an MHL cable including an HDMI Type Aplug 310, thereby allowing for connection with an MHL sink having anHDMI connector receptacle. In some embodiments, the cable 300 includes aresistance (R_(CABLE) _(—) _(DETECT) _(—) _(TYPE) _(—) _(A) _(—)_(PLUG)) 305 that operates to link two of a plurality of pins, such as afirst pin and a second pin, of the connector plug together. In anexample of an HDMI Type A plug, the first pin 315 may be Pin #15 of theconnector, where such pin will be linked to a pull-up element(CD_PULLUP) when connected to an MHL sink device; and the second pin 320may be Pin #2 of the connector, where such pin will be connected to avoltage sensing node (CD_SENSE) when connected to an MHL sink device.

In some embodiments, a sink device may further use a value of theresistance 305 in identification of the cable. In one example, a firstcable may utilize a first resistance (such as 3.3 kΩ), while anotherversion of a cable, such as a later cable with an improved feature set,may utilize a second resistance (such as 4.3 kΩ). In some embodiments, asink device may utilize the detected resistance to determine the type ofcable and thus the features of an attached cable.

FIG. 4 illustrates an embodiment of a sink device to detect cableconnections. In some embodiments, a sink device 400 compatible with afirst, such as an MHL sink device, includes a connector (such as areceptacle for a plug) 410, such as, for example, an HDMI Type Areceptacle. The connector 410 receives a plurality of pin connections,including a first pin 415 (which may be Pin #15 of the connector forCD_PULLUP) and a second pin 420 (which may be Pin #2 of the connectorfor CD_SENSE). In some embodiments, the first pin 415 of the connector410 is coupled with a first end of a pull-up resistor 430 (R_(PULLUP)_(—) _(TYPE) _(—) _(A) _(—) _(REC)), where a second end of the pull-upresistor 430 is coupled with a voltage potential 425 (V_(TERM) _(—)_(CABLE) _(—) _(DETECT) _(—) _(TYPE) _(—) _(A)). In some embodiments,the second pin 420 of the connector 410 is coupled with a sense node 445(CD_SENSE) for sensing of a voltage potential in order to determine theconnection of a cable. In some embodiments, the sink device 400 furtherincludes a pull-down resistor 435 (R_(CABLE) _(—) _(DETECT) _(—) _(TYPE)_(—) _(A) _(—) _(REC)) and pull-down capacitor 440 (C_(CABLE) _(—)_(DETECT) _(—) _(TYPE) _(—) _(A) _(—) _(REC)), where a first end of theresistor 435 and the capacitor 440 are coupled with the sense node 445and a second end of the resistor and capacitor are coupled to ground. Insome embodiments, the capacitor provides a path to ground for AC(alternating current) signals for second protocol (HDMI) operation,while there is a high impedance path to ground for sensing for a firstprotocol cable. In some embodiments, the sink device 400 includes avoltage detection element 450 to detect the voltage potential on thesense node 445, where the voltage detection element may be any knownmechanism for the detection of a voltage. In the first protocol (MHL)the pull-down resistor provides a voltage drop, where a value of thepull-down resistor is provided such that in series with the pull-upresistor (which as a set value in HDMI specification) to provide adetectable logic voltage value a In some embodiments, if a voltage atthe sense node is greater than a certain threshold voltage, then aconnection to a first protocol cable at the receptacle is detected, andthe sink device may proceed with operations for the first protocol,including discovery of a connected device. In some embodiments, thevalues of the resistors 430 and 435 are selected, together with thevalue of a resistance of a connector, are utilized to generate one ormore voltages at the sense node 445.

In some embodiments, the HDMI Type A connector is utilized to connectwith a receptacle. In some embodiments, a MHL Sink uses a receptacle toconnect to an upstream source device via an MHL Cable. In someembodiments, the sink is responsible for managing the detection of theproper mode or proper cable, and protecting the pins and contacts fromdamage during that detection process. In some embodiments, a MHL sink isoperable such it does not drive signal levels onto the MHL+, MHL− orCBUS signal pins, and does drive any voltage on VBUS, in a manner thatmay damage a non-MHL device connected to this receptacle.

FIG. 5A is an illustration of pins for a cable connection to a sourcedevice in an embodiment of a system. In some embodiments, a cableprovides certain connections for a first protocol, such as MHL. In someembodiments, connections may be for a Micro USB connection to an MHLdevice. Pursuant to the MHL protocol requirements, the connectionsinclude five wire connections, such connections being a voltage bus(VBUS) for providing a voltage to an MHL, data lines (MHL− and MHL+), acontrol bus (CBUS), and a ground connection (GND), in addition to ashield connection (linked to a cable shell). The USB signal namesassociated with the contact numbers in FIG. 5A may be found in the“Universal Serial Bus Micro-USB Cables and Connectors Specification,Revision 1.01” (April 2007).

FIG. 5B is an illustration of pins for a cable connection to a sinkdevice in an embodiment of a system. In some embodiments, a cableproviding the connections illustrated in FIG. 5A for a source deviceprovides pin connections in a second protocol compatible connector, suchas an HDMI connector, for a CD_SENSE node and a CD_PULLUP connection fordetection of a cable connection. In some embodiments, the CD_SENSE nodeand a CD_PULLUP are coupled via a resistance, and are not linked to asource device. The pin connections for cable detection in addition toconnections related to the first protocol, such as MHL relatedconnections for a MHL+, MHL−, and TMDS ground for data transmission; avoltage bus (VBUS) and control bus (CBUS) with a VBUS and CBUS ground;and shield (cable shell) and MHL shield connections. “N/C” indicates apin that is not used by MHL and is not connected to any other signal orlevel in the sink end of the MHL cable.

In some embodiments, a connector for connection of a first communicationstandard to a second communication standard, such as a connectionbetween MHL and HDMI, utilizing the mapping of the connection from thefirst communication standard to the second communication standard. Insome embodiments, a connector such as an HDMI Type A connector (whichmay be either a plug or receptacle connector element), includes themapping of the five MHL connections provide in FIG. 5A to the contactnumbers for the HDMI type A connector as shown in FIG. 5B.

In some embodiments, MHL_Shield, TMDS_GND and VBUS_CBUS_GND may beconnected at the system level to a ground signal defined in the MHLSpecification. In some embodiments, MHL_Shield is intended to be closelyassociated with the MHL+ and MHL− signals and VBUS_CBUS_GND is intendedto be closely associated with the VBUS and CBUS pins in order to meetelectrical requirements of the MHL Specification.

FIG. 6A is an illustration of parameters for an embodiment of a sinkdevice to detect cable connections. FIG. 6B is an illustration of aparameter for an embodiment of a cable for connection of a source deviceto a sink device. As provided in FIG. 6A, in some embodiments, a cabledetect pull-up resistor (such as resistor 430 in FIG. 4) has a typicalresistance of 47 KΩ; a cable detect pull-down resistor (resistor 435 inFIG. 4) has a typical resistance of 300 KΩ; a cable detect pull-downcapacitor (capacitor 440 in FIG. 4) has a typical capacitance of 47 nF.As provided in FIG. 6B, a cable detection plug resistor (resistor 305 inFIG. 3) has a smaller typical resistance of 3.3 KΩ, where suchresistance is small enough to have a minor effect on the voltage valuesdeveloped by the elements of the sink device, but is a sufficientresistance to protect a circuit if a connection between a voltage andground is generated by an improper connection to the cable.

In some embodiments, utilizing the cable pull-up and pull-down elementsin connection with the resistance of the cable the CD_PULLUP andCD_SENSE pins, a voltage may be sensed at the CD_SENSE node. In someembodiments, if the voltage is higher than a threshold such as thedetection input high voltage of 2.0 volts, then the sink device maydetermine that a first protocol cable is connected to the sink device.In some embodiments, if the voltage is less than a threshold such as thedetection input low voltage of 0.8 volts, then the sink device maydetermine that a first protocol cable is not connected to the sinkdevice. In some embodiments, a voltage between such values may be anindeterminate result.

FIG. 7 illustrates an embodiment of an electronic device. In thisillustration, certain standard and well-known components that are notgermane to the present description are not shown. In some embodiments, adevice 700 may be a sink device compatible with a first protocol, suchas an MHL sink device, that may receive a cable connection from anotherdevice. In some embodiments, the device 700 may be a source deviceconnected via cable to a device.

Under some embodiments, the device 700 comprises an interconnect orcrossbar 705 or other communication means for transmission of data. Thedata may include various types of data, including, for example,audio-visual data and related control data. The device 700 may include aprocessing means such as one or more processors 710 coupled with theinterconnect 805 for processing information. The processors 710 maycomprise one or more physical processors and one or more logicalprocessors. Further, each of the processors 710 may include multipleprocessor cores. The interconnect 705 is illustrated as a singleinterconnect for simplicity, but may represent multiple differentinterconnects or buses and the component connections to suchinterconnects may vary. The interconnect 705 shown in FIG. 7 is anabstraction that represents any one or more separate physical buses,point-to-point connections, or both connected by appropriate bridges,adapters, or controllers. The interconnect 705 may include, for example,a system bus, a PCI or PCIe bus, a HyperTransport or industry standardarchitecture (ISA) bus, a small computer system interface (SCSI) bus, aIIC (I2C) bus, or an Institute of Electrical and Electronics Engineers(IEEE) standard 1394 bus, sometimes referred to as “Firewire”.(“Standard for a High Performance Serial Bus” 1394-1995, IEEE, publishedAug. 30, 1996, and supplements)

In some embodiments, the device 800 further comprises a random accessmemory (RAM) or other dynamic storage device as a main memory 715 forstoring information and instructions to be executed by the processors710. Main memory 715 also may be used for storing data for data streamsor sub-streams. RAM memory includes dynamic random access memory (DRAM),which requires refreshing of memory contents, and static random accessmemory (SRAM), which does not require refreshing contents, but atincreased cost. DRAM memory may include synchronous dynamic randomaccess memory (SDRAM), which includes a clock signal to control signals,and extended data-out dynamic random access memory (EDO DRAM). In someembodiments, memory of the system may certain registers or other specialpurpose memory. The device 700 also may comprise a read only memory(ROM) 725 or other static storage device for storing static informationand instructions for the processors 710. The device 700 may include oneor more non-volatile memory elements 730 for the storage of certainelements.

Data storage 720 may also be coupled to the interconnect 705 of thedevice 700 for storing information and instructions. The data storage720 may include a magnetic disk or other memory device. Such elementsmay be combined together or may be separate components, and utilizeparts of other elements of the device 700.

The device 700 may also be coupled via the interconnect 705 to an outputdisplay or presentation device 740. In some embodiments, the display 740may include a liquid crystal display (LCD), plasma display, or any otherdisplay technology for displaying information or content to an end user.In some environments, the display 740 may include a touch-screen that isalso utilized as at least a part of an input device. In someenvironments, the display 740 may be or may include an audio device,such as a speaker for providing audio information, including the audioportion of a television program.

One or more transmitters or receivers 745 may also be coupled to theinterconnect 705. In some embodiments, the device 700 may include one ormore ports 750 for the reception or transmission of data. In someembodiments, at least one port may utilize a connector (such as areceptacle for a cable plug) compatible with a second protocol, such anHDMI compatible connector. In some embodiments, the device 700 operatesto detect a cable connection for a first protocol device by thedetection of a certain voltage at a sense pin of the connector, such asa voltage that is above a certain threshold.

The device 700 may further include one or more antennas 755 for thereception of data via radio signals. The device 700 may also comprise apower device or system 760, which may comprise a power supply, abattery, a solar cell, a fuel cell, or other system or device forproviding or generating power. The power provided by the power device orsystem 760 may be distributed as required to elements of the device 700.

In the description above, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. It will be apparent, however, toone skilled in the art that the present invention may be practicedwithout some of these specific details. In other instances, well-knownstructures and devices are shown in block diagram form. There may beintermediate structure between illustrated components. The componentsdescribed or illustrated herein may have additional inputs or outputsthat are not illustrated or described. The illustrated elements orcomponents may also be arranged in different arrangements or orders,including the reordering of any fields or the modification of fieldsizes.

The present invention may include various processes. The processes ofthe present invention may be performed by hardware components or may beembodied in computer-readable instructions, which may be used to cause ageneral purpose or special purpose processor or logic circuitsprogrammed with the instructions to perform the processes.Alternatively, the processes may be performed by a combination ofhardware and software.

Portions of the present invention may be provided as a computer programproduct, which may include a computer-readable storage medium havingstored thereon computer program instructions, which may be used toprogram a computer (or other electronic devices) to perform a processaccording to the present invention. The computer-readable storage mediummay include, but is not limited to, floppy diskettes, optical disks,CD-ROMs (compact disk read-only memory), and magneto-optical disks, ROMs(read-only memory), RAMs (random access memory), EPROMs (erasableprogrammable read-only memory), EEPROMs (electrically-erasableprogrammable read-only memory), magnet or optical cards, flash memory,or other type of media/computer-readable medium suitable for storingelectronic instructions. Moreover, the present invention may also bedownloaded as a computer program product, wherein the program may betransferred from a remote computer to a requesting computer.

Many of the methods are described in their most basic form, butprocesses may be added to or deleted from any of the methods andinformation may be added or subtracted from any of the describedmessages without departing from the basic scope of the presentinvention. It will be apparent to those skilled in the art that manyfurther modifications and adaptations may be made. The particularembodiments are not provided to limit the invention but to illustrateit.

If it is said that an element “A” is coupled to or with element “B,”element A may be directly coupled to element B or be indirectly coupledthrough, for example, element C. When the specification states that acomponent, feature, structure, process, or characteristic A “causes” acomponent, feature, structure, process, or characteristic B, it meansthat “A” is at least a partial cause of “B” but that there may also beat least one other component, feature, structure, process, orcharacteristic that assists in causing “B.” If the specificationindicates that a component, feature, structure, process, orcharacteristic “may”, “might”, or “could” be included, that particularcomponent, feature, structure, process, or characteristic is notrequired to be included. If the specification refers to “a” or “an”element, this does not mean there is only one of the described elements.

An embodiment is an implementation or example of the invention.Reference in the specification to “an embodiment,” “one embodiment,”“some embodiments,” or “other embodiments” means that a particularfeature, structure, or characteristic described in connection with theembodiments is included in at least some embodiments, but notnecessarily all embodiments. The various appearances of “an embodiment,”“one embodiment,” or “some embodiments” are not necessarily allreferring to the same embodiments. It should be appreciated that in theforegoing description of exemplary embodiments of the invention, variousfeatures of the invention are sometimes grouped together in a singleembodiment, figure, or description thereof for the purpose ofstreamlining the disclosure and aiding in the understanding of one ormore of the various inventive aspects.

What is claimed is:
 1. An apparatus comprising: a port for theconnection of a first end of a cable, the port being compatible with afirst protocol and a second protocol, the port including a connector forthe second protocol, the port including a plurality of pins including afirst pin, a second pin, and a power pin; a pull-up resistor coupledbetween the first pin and a voltage source, wherein the pull-up resistoris a resistor required for the second protocol; a pull-down resistorcoupled between the second pin and ground; and a voltage detectionelement coupled with the second pin; wherein the apparatus is todetermine that a cable compatible with the first protocol is connectedto the port if the voltage detection element detects a voltage above afirst threshold, wherein a cable compatible with the first protocolincludes a resistor linking the first pin and the second pin together;and wherein the first protocol includes a discovery sequence betweenconnected devices, and wherein the apparatus is to supply a voltage onthe power pin upon determining based upon the voltage detected by thevoltage detection element that a cable compatible with the firstprotocol is connected to the connector without requiring a successfuldiscovery sequence for the apparatus and a connected device.
 2. Theapparatus of claim 1, wherein the apparatus is to determine that a cablecompatible with the first protocol is not connected to the port if thevoltage detection element detects a voltage below a second threshold,the second threshold being lower than the first threshold.
 3. Theapparatus of claim 1, wherein the first protocol is MHL (MobileHigh-Definition Link) and the second protocol is HDMI (High DefinitionMultimedia Interface).
 4. The apparatus of claim 1, further comprising apull-down capacitor coupled between the second pin and ground.
 5. Theapparatus of claim 1, wherein the apparatus is a device that iscompatible with data transfer in the first protocol and in the secondprotocol.
 6. The apparatus of claim 1, wherein the apparatus is furtherto detect a type of cable of a plurality of types of cables compatiblewith the first protocol based on a resistance value of the cable.
 7. Asystem comprising: a sink device that is compatible with a firstprotocol and a second protocol, the sink device including: a port havinga connector for the second protocol, the port including a plurality ofpins including a first pin, a second pin, and a power pin, a pull-upresistor coupled between the first pin and a voltage source, wherein thepull-up resistor is a resistor required for the second protocol, apull-down resistor coupled between the second pin and ground, and avoltage detection element coupled with the second pin; and a cable witha first end and a second end coupled with the sink device, the cableincluding a connector for the second protocol attached to the first endof the cable, the connector including a first pin to connect with thefirst pin of the port and a second pin to connect with the second pin ofthe port, wherein a cable compatible with the first protocol includes aresistor linking the first pin of the cable connector and the second pinof the cable connector together; wherein the sink device is to determinethat the cable is compatible with the first protocol if the voltagedetection element detects a voltage above a first threshold; and whereinthe first protocol includes a discovery sequence between connecteddevices, and wherein the sink device is to supply a voltage on the powerpin upon determining based upon the voltage detected by the voltagedetection element that a cable compatible with the first protocol isconnected to the connector without requiring a successful discoverysequence for the sink device and a connected device.
 8. The system ofclaim 7, wherein the first protocol is MHL (Mobile High-Definition Link)and the second protocol is HDMI (High Definition Multimedia Interface).9. The system of claim 7, wherein the cable includes a second connectorat the second end of the cable, and wherein the first pin and the secondpin are not connected to any pins of the second connector for a cablecompatible with the first protocol.
 10. The system of claim 9, furthercomprising a source device coupled with the second connector, whereinthe source device is compatible with the first protocol or the secondprotocol.
 11. The system of claim 7, wherein the resistor of a cablecompatible with the first protocol has a resistance that is smaller thana resistance of the pull-up resistor or the pull-down resistor.
 12. Thesystem of claim 7, further comprising a pull-down capacitor coupledbetween the second pin and ground, the pull-down capacitor proving apath for AC (alternating current) signals to ground.
 13. The system ofclaim 7, wherein the sink device is to determine that the cable is notcompatible with the first protocol if the voltage detection elementdetects a voltage below a second threshold voltage, the second thresholdvoltage being lower than the first threshold voltage.
 14. The system ofclaim 7, wherein the sink device is further to detect a type of cable ofa plurality of types of cables compatible with the first protocol basedon a resistance value of the cable.
 15. A method comprising: receiving acable at a connector of a device; connecting the first pin of theconnector of the device to a first end of a pull-up resistor, a secondend of the pull-up resistor being coupled with a voltage source, thedevice being compatible with a first protocol and a second protocol, thepull-up resistor being required for the second protocol, wherein a cablecompatible with the first protocol includes a resistor linking a firstpin and a second pin of the connector together; connecting the secondpin of the connector of the device to a first end of a pull-downresistor and a node, a second end of the pull-down resistor beingcoupled with ground; detecting a voltage on the node; and determining bythe device that a cable compatible with the first protocol is coupledwith the connector if the detected voltage is above a threshold voltage;wherein the first protocol includes a discovery sequence betweenconnected devices, and wherein the apparatus is to supply a voltage onthe power pin upon determining based upon the voltage detected by thevoltage detection element that a cable compatible with the firstprotocol is connected to the connector without requiring a successfuldiscovery sequence between the device and a second connected device. 16.The method of claim 15, further comprising determining that a cablecompatible with the first protocol is not connected with the connectorif the voltage detection element detects a voltage on the node that isbelow a second threshold, the second threshold being lower than thefirst threshold.
 17. The method of claim 15, wherein the first protocolis MHL (Mobile High-Definition Link) and the second protocol is HDMI(High Definition Multimedia Interface).
 18. The method of claim 15,further comprising connecting the second pin of the connector of thedevice with a first end of a pull-down capacitor, a second end of thepull-down capacitor being coupled with ground.
 19. The method of claim15, further comprising detecting a type of cable of a plurality of typesof cables compatible with the first protocol based on a resistance valueof the cable.
 20. The apparatus of claim 1, wherein for the secondprotocol a voltage is received on the power pin in a reverse directionfrom the supplying of the voltage on the power pin by the apparatusaccording to the first protocol.
 21. The system of claim 7, wherein forthe second protocol a voltage is received on the power pin in a reversedirection from the supplying of the voltage on the power pin by thesource device according to the first protocol.
 22. The method of claim15, further comprising receiving a voltage on the power pin according tothe second protocol in a reverse direction from the supplying of thevoltage on the power pin by the source device according to the firstprotocol.